Internal validity

Internal validity means that you can be sure that the results obtained in an experiment or study are true or accurate. It means that the results are a result of the experiment or study itself and not of any other outside factors. Think of it like this: If you want to test whether drinking a glass of water every day can make you healthier, you need to make sure that it is only the water you are drinking that affects your health, and not something else like eating more vegetables or exercising more. Internal validity makes sure that only one thing (the water) is responsible for the results.